Ultrathin film electrodeposition of polythiophene conjugated networks through a polymer precursor route

The electrodeposition of polysiloxane precursor polymers to form cross-link ed conjugated polythiophene ultrathin films is described. The precursor pol ymer contains a polysiloxane backbone with pendant electroactive thiophene monomer units synthesized via a hydrosilylation reaction. The thiophene uni ts were electropolymerized by cyclic voltammetry. Investigations were made on the oxidation and reduction of the thiophene monomer and the polymers fo rmed. A uniformly smooth layer-by-layer growth of the film was observed by repeated cycling based on the cyclic voltammogram, surface plasmon spectros copy (SPS), and the atomic force microscopy images. The morphology of the f ilm changed with increasing number of cycles being transformed from a relat ively globular to a more membranelike morphology. Correlation was also made on the morphological changes with the electropolymerization process and th e extent of crosslinking. UV-vis spectra showed clear evidence of polythiop hene structure formation in the cross-linked polymer. SPS confirmed that th e thickness of the deposited polymer film is easily controlled by the numbe r of electrochemical potential cycles.